The 1928 Chevy 4-cylinder I used to work on had a thick felt pad over the rocker arms, the same width as the inside of the valve cover, and oil holes in the cover so the owner could use a squirt can to saturate the felt. It also muffled valve noises.
Later-model engines used the weep holes in the rockers to dribble a little oil down over the valve springs and guides, and some of it finds its way down the valve stems. A properly-fitted valve guide allows a very small trickle of oil to lube the guide and be consumed along with the fuel and air. Leakage down the exhaust valve stem just gets burned in the exhaust stream. Worn guides, intake or exhaust, can contribute to excessive oil consumption just like worn piston rings, often with none of the telltale blue smoke that bad rings produce.
Jerry
